Cathode ray tubes for displaying letters and the like

ABSTRACT

In a cathode ray tube for displaying letters, digits or the like, there are provided pattern forming means positioned between the cathode electrode and the electron lens system of the cathode ray tube, the pattern forming means comprising an insulator substrate provided with a plurality of perforations arranged in a matrix, and a plurality of groups of parallel conductors disposed on the opposite sides of the matrix, each one of the perforations being positioned in a square defined by two pairs of parallel conductors belonging to different groups; and means to selectively apply potentials of the same or opposite polarities upon selected parallel conductors to cause selected ones of the perforations to permit or block the electrons emanated from the cathode electrode from passing through selected perforations to display a desired letter on the display screen of the cathode ray tube.

United States Patent 1 1 Tanji et al.

1 1 Aug. 19, 1975 CATHODE RAY TUBES FOR DISPLAYING LETTERS AND THE LIKE Inventors: Mikiharu Tanji; Yoshimasa Yamanaka; lsao Takahashi, all of lse, Japan (73] Assignee: Ise Electronics Corporation, lse,

Japan [22] Filed: Feb. 7, 1973 [Zll Appl, No.: 330,303

Related US. Application Data [63] Continuation of Ser, No. M1679, Jan 4, I971,

[56] References Cited UNITED STATES PATENTS 2,519,172 8/[950 Brown 3l5/3l R X 2,890,376 6/l959 Van Doorn et al 315/13 R 2,967,972 l/l96l De Haan .4 3l5/l3 R I6\ Y it E is T is

O is

R in) 3/l970 Staar 315/13 R 6/1970 Yamada 3l3/9l X Primary E\uminer-Leland A. Sebastian Axxislunl LimminerP. A. Nelson Attorney, Agem, 0r FirmRobert L. Thompson [57] ABSTRACT In a cathode ray tube for displaying letters, digits or the like, there are provided pattern forming means positioned between the cathode electrode and the electron lens system of the cathode ray tube, the pattern forming means comprising an insulator substrate provided with a plurality of perforations arranged in a matrix, and a plurality of groups of parallel conductors disposed on the opposite sides of the matrix, each one of the perforations being positioned in a square defined by two pairs of parallel conductors belonging to different groups; and means to selectively apply potentials of the same or opposite polarities upon selected parallel conductors to cause selected ones of the perforations to permit or block the electrons emanated from the cathode electrode from passing through selected perforations to display a desired letter on the display screen of the cathode ray tube.

3 Claims, 5 Drawing Figures illllll X SELECTOR 1 'CATHODE RAY TUBES FOR DISPLAYING LETTERS AND THE LIKE CROSS REFERENCE TO RELATED APPLICATION This application is a continuation of applicants copending application, Ser. No. l03,679, filed on Jan. 4, l97l, and now abandoned.

BACKGROUND OF THE INVENTION This invention relates to a cathode ray tube for displaying a letter, digit, symbol (for the sake of brevity hereinafter, merely termed letter).

Although cathode ray tubes of various constructions have been proposed for displaying letters such as the Typotron or Charactron, in these prior tubes it has been necessary to use deflection plates to select a desired letter which requires extremely high accuracy for the working of electron guns thus rendering them very difficult to manufacture.

SUMMARY OF THE INVENTION It is an object of this invention to provide a novel cathode ray tube for displaying letters and the like which is simple in construction and requires less accuracy of deflection.

Another object of this invention is to provide an improved cathode ray tube for displaying letters and the like wherein the position and magnitude ofa pattern of letter focused on the display screen can be varied as desired by varying the power supplied to the deflection means.

A further object of this invention is to provide a cathode ray tube including novel letter forming means capable of displaying letters and the like of different configurations.

Still further object of this invention is to provide a novel cathode ray tube normally utilized for displaying letters and the like but which can also be used as a conventional cathode ray tube.

In accordance with this invention these and other objects can be attained by providing, in a cathode ray tube of the type comprising an evacuated envelope having a display screen at one end thereof, a cathode electrode at the other end for emitting electrons and an electron lens system including deflection means, a pattern forming means positioned between the cathode electrode and the electron lens system, the pattern forming means including an insulator substrate provided with a plurality of perforations arranged in a matrix, and a plurality of groups of parallel conductors disposed on the opposite sides of the substrate to form rows and columns of the matrix, each one of the perforations being positioned in a square defined by two pairs of parallel conductors belonging to different groups; and means to selectively apply potentials of the same or opposite polarities upon selected parallel con ductors to cause selected ones of the perforations defined by the selected conductors to permit or block the electrons from passing through the selected perforations toward the display screen to display thereon a desired letter.

Advantageously there is provided a control grid between the cathode electrode and the pattern forming means for uniformly dispersing the electrons and an accelerating electrode between the pattern forming means and the electron lens system.

.imr me BRIEF DESCRIPTION OF THE DRAWING The invention can be more fully understood from the following description taken in conjunction with the accompanying drawing in which:

FIG. 1 is a diagrammatic longitudinal sectional view ofa cathode ray tube for displaying a letter constructed in accordance with this invention;

FIG. 2 is a plan view of one example of a substrate constituting a portion of a pattern forming means shown in FIG. I;

FIG. 3 is an enlarged plan view of groups of X and Y lines comprising a portion of the pattern forming means shown in FIG. 1;

FIG. 4 is an enlarged sectional view of a combination of the substrate and groups of X and Y lines shown in FIGS. 2 and 3; and

FIG. 5 is a diagram to explain the operation of the pattern forming means.

DESCRIPTION OF THE PREFERRED EMBODIMENT The preferred embodiment of a novel cathode ray tube illustrated in FIG. 1 comprises an elongated glass envelope 1, a face plate or a fluorescent display screen secured to the front end of the envelope, a focusing coil 3 disposed to surround the neck of the envelope to act as an electron lens system, a deflection coil 4 also disposed to surround the neck but in front of the electron lens system, a cathode electrode 5 and a grid electrode 6 of a mesh construction and disposed in front of the cathode electrode 5 for uniformly dispersing electrons. According to this invention. a letter pattern forming means 7 is disposed in front of the grid electrode for forming the pattern of a letter by means of electrons. A short cylindrical acceleration electrode 8 is provided in front of the letter pattern forming means. As usual, the opposite end of the envelope is sealed by a stem 9 including a plurality of leads 10 which are sealed to the stem 9 for interconnecting component parts in the envelope and the external circuits, not shown.

In operation, the electrons emanated from the cathode electrodes are dispersed uniformly by the grid electrode 6 to impringe upon letter forming means 7 which acts to select a desired letter pattern with a pattern of an electron beam which is accelerated by acceleration electrode 8, diverged by the electron lens system comprised by focusing coil 3 and is then deflected by deflection coil 4 to impinge upon the fluorescent display screen 2. In this manner, the desired letter pattern is displayed on the screen 2, and the position and dimensions of the displayed pattern are controlled by the current supplied to the deflection coil 4.

Letter forming means 7 is comprised by a substrate 11 shown in FIG. 2 and groups ofX and Y lines 12 and 13 shown in FIG. 3.

As shown in FIG. 2, substrate II comprises a relatively thin insulative flat disc of ceramic or mica, for example, having a circular configuration conforming to that of the envelope 1. The substrate is formed with a plurality of perforations 14 which are arranged in a matrix and the substrate is disposed at right angles to the axis of the envelope 1.

As shown in FIG. 4, the group of the X lines 12 are disposed on one side of substrate 11 while the group of Y lines 13 are on the opposite side. Lines 12 and I3 are regularly spaced apart to contain one perforation 14 in each square formed between adjacent pairs of conductors l2 and 13.

With the letter forming means 7, a digit 1, for example, can be displayed in the following manner with reference to FIG. in which for the sake of simplicity only the groups of X and Y lines 12 and 13 are shown respectively consisting of ten conductors X through X and ten conductors Y through Y In practice the arrangement extends, of course, over the entire matrix of perforations 14 in substrate 11.

Where lines X and X and lines Y Y Y Y Y Y and Y are selected (perfect selection), an electron group for displaying a display pattern of the digit 1 is formed. In this case, potentials are impressed by X selector upon lines X X and by Y selector 16 upon lines Y to Y inclusive to cause them to create positive fields with the remainder of the lines impressed to create negative field. In a square defined by lines X X Y and Y for example, fields created by the potentials impressed upon these lines superpose each other so that electrons which have emanated from cathode electrode 5 and have passed through grid electrode 6 pass through perforation 14 of substrate ll positioned in that square. Other squares defined by lines X X Y Y Y Y Y and Y similarly permit electrons to pass through them freely. In this manner, an electron pattern displaying a digit 1 is formed by dots P through P,,, as shown in FIG, 5.

On the other hand, potentials are impressed upon remaining X and Y lines which were not selected so as to cause them to create negative fields so that in the squares defined by these lines, typically a square defined by lines X X Y and Y negative fields created by respective lines superpose each other with the result that electrons emanated from cathode electrode 5 are prevented from passing through these squares. In a partially selected square, typically a square defined by lines X X Y and Y a positive field created by lines X Y and Y and negative field created by line X superpose each other so that in such a square a positive field of an intensity of one-half of that of the perfect selection described above is formed. Consequently, electrons can scarcely pass through the perforation 14 at such a square and even when a small number of electrons may pass through the perforation they will be pulled back by the positive field.

The novel cathode ray tube for displaying letters has the following advantages:

A. As distinguished from the conventional cathode ray tube wherein desired patterns are formed by defleeting an electron beam, in the novel tube herein disclosed the desired patterns are formed by selectively exciting groups of X and Y lines which are arranged in a matrix so that the construction ofthe display tube can be greatly simplified. Moreover, the accuracy of deflection required is not so high as in the prior art tube.

B. Since an electron lens system including a deflecting means is situated in front of the pattern forming means, the electron beam itself passing through the electron beam system forms the information thus enabling operation to vary as desired the magnitude and position of the pattern focused on the display screen by varying the electric power supplied to the deflection means.

C. With the pattern forming means described above, it is possible to display various patterns on the same display screen.

D. Where the groups of X and Y lines comprising the pattern forming means are maintained at the same potential, the display tube can be used in the same manner as the conventional cathode ray tube.

While the invention has been shown and described in terms of a preferred embodiment thereof it is to be understood that the invention is not limited to such specific embodiment and that many changes and modifications may be made without departing from the true spirit and scope of the invention as defined in the appended claims.

We claim:

I. In a cathode ray tube for displaying letters of the type comprising an evacuated envelope having a display screen at one end thereof, a cathode electrode at the other end for emitting electrons and an electron lens system including deflection means, the improvement which comprises pattern forming means positioned between said cathode electrode and said electron lens system, said pattern forming means including an insulator substrate provided with a plurality of perforations arranged in a matrix, and a plurality of groups of parallel conductors disposed on the opposite sides of said substrate to form rows and columns of said matrix, each one of said perforations being positioned in a square defined by two pairs of parallel conductors belonging to different groups; and means for selectively applying potentials of the same or opposite polarities upon all of said parallel conductors to cause selected ones of said perforations in squares defined by pairs of said selected conductors on opposite sides of said substrate energized with the same polarity potential to have a superposed positive field of predetermined magnitude to permit said electrons to pass through said selected ones of said perforations toward said display screen to display thereon a desired letter, the remainder of said perforations having a superposed field intensity that is negative relative to any value of field intensity greater than half said positive field of predetermined magnitude.

2. The cathode ray tube according to claim 1 wherein a control grid is disposed between said cathode electrode and said pattern forming means for uniformly dispersing said electrons.

3. The cathode ray tube according to claim I wherein an accelerating electrode is provided between said pattern forming means and said electron lens system. 

1. In a cathode ray tube for displaying letters of the type comprising an evacuated envelope having a display screen at one end thereof, a cathode electrode at the other end for emitting electrons and an electron lens system including deflection means, the improvement which comprises pattern forming means positioned between said cathode electrode and said electron lens system, said pattern forming means including an insulator substrate provided with a plurality of perforations arranged in a matrix, and a plurality of groups of parallel conductors disposed on the opposite sides of said substrate to form rows and columns of said matrix, each one of said perforations being positioned in a square defined by two pairs of parallel conductors belonging to different groups; and means for selectively applying potentials of the same or opposite polarities upon all of said parallel conductors to cause selected ones of said perforations in squares defined by pairs of said selected conductors on opposite sides of said substrate energized with the same polarity potential to have a superposed positive field of predetermined magnitude to permit said electrons to pass through said selected ones of said perforations toward said display screen to display thereon a desired letter, the remainder of said perforations having a superposed field intensity that is negative relative to any value of field intensity greater than half said positive field of predetermined magnitude.
 2. The cathode ray tube according to claim 1 wherein a control grid is disposed between said cathode electrode and said pattern forming means for uniformly dispersing said electrons.
 3. The cathode ray tube according to claim 1 wherein an accelerating electrode is provided between said pattern forming means and said electron lens system. 